Method for producing a roll grinder with minimal gap dimensions between the running roller and the handle body

ABSTRACT

A method for producing a roll grinder with two running rollers, a handle body arranged between the running rollers and can be rotated relative thereto, and at least one grinding or polishing surface. The method includes steps of: producing the handle body; measuring the handle body in order to determine the actual dimensions of the handle body; providing at least two differently dimensioned types of spacer elements, by means of each of which a different distance can be set between one of the running rollers and the handle body in the installed state of the roll grinder compared to at least one other type; selecting one of the types of spacer elements provided depending on the measured dimension of the handle body; and connecting the handle body to the running rollers to form the roll grinder while using at least one spacer element of the type selected.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase of International Application No. PCT/EP2021/074647, filed Sep. 8, 2021, which claims priority to German Application No. 10 2020 123 499.6, filed Sep. 9, 2020.

BACKGROUND

The present disclosure relates to a method for producing a roll grinder/rolling sharpener with two running rollers/rollers, a handle body arranged between the rollers and rotatable relative thereto, and with at least one grinding/sharpening or polishing surface.

Roll grinders/rolling sharpeners are used for grinding/sharpening and/or polishing cutting tools and are known, inter alia, from EP 3 278 928 A or DE 20 2020 001 180 U1. The sharpening or polishing surface of the roll grinder is brought into contact with a cutting edge of the cutting tool to be ground/sharpened and moved along the cutting edge in a rolling motion over a flat base.

In the roll grinder known from DE 20 2020 001 180 U1, the rollers may be rotated independently of one another relative to the handle body. This impedes the directional stability of the roll grinder and easily causes the rollers to tilt relative to the handle body. Thus, there must be sufficient clearance between the rollers and the handle body to ensure rotation of the rollers relative to the handle body. For precise grinding/sharpening of a knife edge, directional stability of the roll grinder is advantageous. EP 3 278 928 A discloses that the rollers are connected via an axle and can thus only be rotated together relative to the handle body. On the one hand, this allows easier guidance of the roll grinder in a straight line along the cutting edge of the cutting tool to be machined, and on the other hand, the rollers are stabilized relative to the handle body so that tilting of the rollers relative to the handle body may be significantly reduced.

Thus, in a roll grinder/rolling sharpener, on the one hand, the rollers must rotate well relative to the handle body, and on the other hand, the distances between the rollers and the handle body should be as small and uniform as possible in order to prevent dirt or moisture from entering the gap, in particular when cleaning the roll grinder.

SUMMARY

Embodiments discussed herein are based on the object of providing a method for producing a roll grinder/rolling sharpener, with which high-quality roll grinders/rolling sharpeners with small and uniform gap dimensions may be manufactured economically.

To solve this problem, some embodiments serve the purpose of manufacturing a roll grinder having two rollers, a handle body arranged between the rollers and rotatable relative thereto, and at least one grinding or polishing surface, and includes the steps:

-   -   Step A: producing the handle body.     -   Step B: measuring the handle body in order to determine an         actual dimension of the handle body.     -   Step C: providing at least two differently dimensioned types of         spacer elements, by means of which in each case a distance         (influenced in particular by the actual dimension of the handle         body) between one of the rollers and the handle body in the         mounted state of the roll grinder may be determined differently         in comparison with at least one other type.     -   Step D: selecting one of the types of spacer elements provided         in step C depending on the dimension determined in step B.     -   Step E: connecting the handle body measured in step B to the         rollers to form the roll grinder using at least one spacer         element of the type selected in step D.

By selecting a suitable spacer element from a plurality of types of spacer elements provided, unavoidable manufacturing tolerances in the production of the handle body may be compensated for particularly easily. The spacer element is generally the least expensive component of the roll grinder and may be manufactured particularly economically in various dimensions. Thus, despite existing dimensional deviations of the handle body from the design specifications, minimum and uniform distances, in particular gap dimensions, may be ensured without reworking the handle body. Preferably, at least 5 different spacer elements are provided, whose dimensions differ from each other by 0.1 mm or 0.05 mm in the dimension to be compensated.

It may be useful if the handle body in step A is made of metal and/or plastic and/or wood, preferably oak wood, walnut wood, beech wood or spruce wood, preferably in one piece. A handle body made of wood has an appealing feel. The handle body may have an untreated or painted surface.

It may prove helpful to have a moisture content of the wood in step A of at most 15%, preferably at most 10%, preferably at most 7%. The use of wood as a construction material for the base body presents a challenge in the manufacture of the roll grinder with respect to maintaining manufacturing tolerances. Since the shape of a wooden body may change as a function of moisture content, among other factors, it is advantageous if the wood used to manufacture the handle body has as little residual moisture as possible.

It may also be useful, however, if the handle body is manufactured in step A as a cylinder, preferably a hollow cylinder. This configuration proves particularly useful when using an axle connecting the rollers, which may be mounted in a central bore of the hollow-cylindrical handle body.

It can also be advantageous, however, if in step B a distance between two parallel sides, preferably a distance between the end faces and/or a distance between two bearing support sections and/or a distance between one of the end faces and the corresponding bearing support section, of the handle body is determined as a dimension of the handle body. The axial length of the handle body, which is preferably measured along a common axis of rotation of the rollers, may be an important factor in determining the gap dimension between each of the rollers and the handle body. For a fixed axial spacing of the rollers, the gap to the handle body would decrease as the axial length of the handle body increases and increase as the axial length of the handle body decreases. The spacer element to be arranged axially between the rollers is intended here to ensure a uniform gap between the rollers and the handle body as a function of the actual length of the handle body, including the unavoidable manufacturing tolerances. Since there is a gap to one of the rollers at each end of the handle body, two spacer elements of the same type are preferably used.

It may prove helpful in step E to use rollers made of metal, preferably corrosion-resistant metal, preferably aluminum or stainless steel. Rollers made of metal are low-wear and may be manufactured with high precision or low manufacturing tolerances.

It may be useful if, in step E, each of the rollers is connected, with the interposition of a spacer element selected in step D, to an axle to be rotatably mounted on or in the handle body, preferably non-positively and/or non-rotatably and/or non-releasably, preferably by press-fitting/joining (pressing). In this way, the rollers may only move together relative to the handle body, thereby enabling directional stability of the roll grinder and increasingly impeding tilting of the rollers relative to the handle body. Press fitting/joining connects the roller and the axle in such a way that an interference fit is produced at the joints after joining. In this way, longitudinal and transverse forces may be transmitted in a force-fit manner.

It may be practical if a stepped axle with a central section and two bearing sections stepped at the ends is used as the axle, with a rolling bearing, one of the spacer elements and one of the rollers being arranged on each bearing section preferably in such a way that the rolling bearing (with the inner ring) is axially supported on the central section and/or the respective spacer element is axially fixed between the rolling bearing (inner ring) and the roller. The axle is made, for example, of plastic and/or metal, preferably corrosion-resistant metal, preferably aluminum or stainless steel. With such an axle design, the distance between the rollers may be optimally adjusted.

It may be useful if each rolling bearing is mounted on the handle body in such a way that it is supported by the outer ring on the handle body or by a bearing sleeve arranged thereon. With such a configuration, the position of the axle as well as the rollers arranged thereon may be optimally set with respect to the handle body. The bearing support section may be formed on the handle body or on a bearing sleeve that may be inserted, for example, into the central bore of the handle body. For example, the outer ring of the rolling bearing is fixed to the handle body by frictional engagement and/or positive engagement.

It may prove helpful if at least one of the rollers has a grinding/sharpening or polishing surface on the end face. In this simple embodiment, the grinding or polishing surface is integral with the roller, so that the roll grinder may be manufactured from a minimal number of components.

It may also be convenient, however, to have at least one grinding/sharpening or polishing disc attached to the roll grinder, wherein the grinding or polishing disc has a grinding or polishing surface. In this more complex embodiment, the grinding or polishing surface is separate from the roller so that each roller may be equipped with a different grinding or polishing disc.

It may also be useful if the grinding or polishing disc is detachably mounted on the roller or axle, preferably by screwing a threaded stud formed on the grinding or polishing disc into a corresponding mating thread. In this way, the grinding or polishing disc may be interchanged with a different grinding or polishing disc to achieve different grinding or polishing effects, or replaced with an identical grinding or polishing disc after appropriate wear.

It may be convenient if each of the rollers has a rubber ring circulating at the edge to form a running surface of the roller. This rubber ring improves the running characteristics of the roll grinder, especially on a hard surface.

It may be advantageous if the roll grinder is manufactured from a maximum of 14, preferably from a maximum of 12 components, preferably from a maximum of 10 components, the components including: the two rollers, the handle roller optionally with two bearing sleeves, two spacer elements, an axle, two rolling bearings, two rubber rings, and at least one grinding disc and/or at least one polishing disc. The rolling bearing counts as one component here. The small number of components reduces manufacturing and storage costs.

A further aspect relates to a method of producing a series of roll grinders using multiple embodiments of the method, wherein in step A at least two handle rollers are manufactured and in step E each handle roller is connected to two rollers to form a roll grinder, in each case using at least one spacer element of the type selected on the basis of the dimension determined in step B, so that the gap dimensions between the rollers and the handle body are within identical tolerance ranges for all the roll grinders, the gap between the handle body and each of the rollers preferably being smaller than 0.5 mm, preferably smaller than 0.2 mm, particularly preferably smaller than 0.1 mm. In particular, when manufacturing a series of roll grinders, whose handle bodies have different dimensions due to unavoidable manufacturing tolerances, the use of different spacer elements for setting the distance between the rollers in the assembled state proves to be particularly advantageous.

Further advantageous embodiments of are obtained from combinations of the features disclosed in the description and the drawings.

Terms and Definitions

A roll grinder/rolling sharpener is understood to be, for example, a roll grinder/rolling sharpener according to EP 3 278 928 A. A roll grinder/rolling sharpener is intended to be brought with its grinding/sharpening or polishing surface into contact with a cutting edge of a cutting tool to be ground/sharpened and, while maintaining contact, is moved in a rolling manner along the cutting edge over a flat base. The contact and relative movement of the cutting edge and the grinding/sharpening or polishing surface removes material from the cutting edge of the cutting tool. As a result, the cutting edge is ground/sharpened or polished. The cutting tool may be fixed in place during grinding/sharpening or polishing by a sharpening jig and positioned at a predetermined grinding/sharpening angle relative to the roll grinder/rolling sharpener.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective exploded view of a roll grinder/rolling sharpener according to the first embodiment, which may be manufactured using the method according to some embodiments.

FIG. 2 is a perspective exploded view of a roll grinder/rolling sharpener according to the second embodiment, which may be manufactured using the method according to some embodiments.

FIG. 3 is a schematic view of the roll grinder/rolling sharpener according to the first embodiment in an assembled state.

FIG. 4 is a schematic view of the roll grinder/rolling sharpener according to the second embodiment in an assembled state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings the preferred embodiments will be described in detail below.

First Embodiment (FIGS. 1 and 3)

In the first embodiment, described below with reference to FIGS. 1 and 3 , the roll grinder/rolling sharpener 1 is constructed from a total of 10 or 12 components and includes two rollers 2, a handle body 3 (optionally with two bearing sleeves, not shown), two spacer elements 4, an axle 5, two rolling bearings 6 (each counting as one component), and two rubber rings 8 arranged on the edges of the rollers 2 to form the running surfaces of the rollers 2.

Each roller 2 is approximately configured as a cylindrical disc made of stainless steel and includes a circumferential annular groove in the cylindrical lateral area 2 a, in which the rubber ring 8 is held positively. The thickness or axial length of the roller 2 is, for example, in the range from 2 to 10 mm, in particular about 8 mm, while the outer diameter (without rubber ring 8) is, for example, in the range from 40 to 60 mm, in particular about 54 mm. The rubber ring 8 preferably has an oval cross-section, the main axis of which is preferably aligned parallel to the lateral area 2 a of the roller 2. On the intended end face of each roller 2 there is an integrally formed grinding/sharpening or polishing surface 1 a, 1 b. The transition from the circumferential side 2 a provided with the annular groove to the end face of the roller 2 is rounded or chamfered, the radius of curvature of the rounding being in the range from 0.5 to 2 mm, in particular about 1 mm. The side of the roller 2 that is intended to face the handle body 3 has a central opening 2 b, with which the roller 2 is fitted onto an axle 5 described below.

The handle body 3 is a hollow cylinder made of wood, which extends along a central axis X3 and has a cylindrical lateral surface 3 a, two parallel end faces 3 b and a cylindrical central bore 3 c. In one variant, the central bore 3 c of the handle body 3 (see FIG. 3 ) includes two sections with different diameters, namely a central section with a smaller diameter and end-side end sections with larger diameters. On the end side of the middle section, two parallel and outwardly facing bearing support sections 3 d are provided for axial support of rolling bearings 6. These bearing support sections 3 d determine the position of the rollers 2 relative to the handle body 3. In an alternative variant, the handle body 3 includes a central bore 3 a of uniform diameter. In this case, in order to fix the rolling bearings 6 described below, a bearing sleeve (not shown) is inserted into the central bore 3 a from each end face 3 a of the handle body 3, which bearing sleeve is supported by a flange on the end face 3 a of the handle body 3 and forms a bearing support section 3 d on a base. The bottom of the bearing sleeve is provided with an opening for the axle 5 to pass through. For particularly high-quality designs, the handle body 3 is made in one piece from oak wood, walnut wood, beech wood or spruce wood. The outer diameter of the handle body 3 preferably corresponds to the outer diameter of the roller 2 (without rubber ring 8), so that the lateral area 3 a of the handle body 3 and the lateral areas 2 a of the rollers 2 are flush with each other in the intended assembly state (see FIG. 3 ). At the time of manufacture of the handle body 3, the moisture content of the wood should be as low as possible and not exceed 10%. The outer diameter of the handle body 3 is in the range of 50 to 60 mm, for example, and in the present case is approximately 54 mm. The axial length of the handle body 3 is, for example, in the range of 55 to 75 mm and in the present case is approximately 64 mm.

The axle 5 is formed as a stepped axle 5 with a central section 5 a and bearing sections 5 b stepped at the ends.

The rolling bearing 6 is, for example, a commercially available ball bearing. The inner diameter of the inner ring of the rolling bearing 6 is matched to the outer diameter of the bearing section 5 b of the axle 5 and may be arranged on the latter, so that the inner ring is supported in the axial direction on the central section 5 a of the axle 5. The outer diameter and axial length of the rolling bearing 6 are matched to the dimensions of the handle body 3. Accordingly, the rolling bearing 6 may be inserted with a precise fit into the central bore or bearing sleeve of the handle body 3 and be supported axially by the outer ring.

The spacer element 4 is, for example, an annular washer or cylindrical sleeve that may be slid onto the bearing section 5 b of the axle 5 to bear against the inner ring of the rolling bearing 6 and a roller 2. There are provided different types of spacer elements 4, which have different axial lengths, in order to precisely set the distance between the rollers 2 to be attached to the axle 5, depending on the actual dimensions L, L1, L2 of the handle body 3—and thus the gap dimension S between each roller 2 and the handle body 3.

In the assembled state, the axle 5 and the spacer elements 4, rolling bearings 6 and rollers 2 connected thereto have a common central or rotational axis X5.

According to the method according to some embodiments, the handle body 3 is manufactured in step A, for example, in one piece from wood in the form of a hollow cylinder.

After manufacturing, the handle body 3 is measured in step B. In this process, the actual dimensions of the handle body 3 are determined, in this case in particular the length L of the handle body 3. Due to manufacturing tolerances and in particular due to the nature of the natural raw material wood, which may change its shape slightly in particular when the moisture content changes, experience has shown that deviations from the design specifications occur.

In order to avoid uneconomical reworking of the handle body 3, various types of spacer elements 4 are provided in step C, which have different axial dimensions and may thus be used depending on the measured length L of the handle body 3 to define the intended gap dimension S between each roller 2 and the handle body 3. It is intended here to make the gap S between each roller 2 and the handle body 3 as small and uniform as possible. For example, five different types of spacer elements 4 are provided for this purpose, which differ in axial length L4 by approximately 0.05 mm, for example.

The distance of the rollers L2 results from the sum of the length L5 of the center section 5 a of the axle 5, the length L4 of both spacer elements 4 and the length L6 of both rolling bearings 6. This distance must correspond to the sum of the length L of the handle body 3 and the two gap dimensions S. This results in the following equation 1:

L+2×S=L5+2×L4+2×L6  Equation 1

Equation 1 may be solved for the length L4 of the spacer elements 4 according to equation 2:

L4=(L+2×S−L5−2×L6)/2  Equation 2

After selecting a type of spacer element 4 from the provided types of spacer elements 4 depending on the determined dimension L of the handle body 3 (step C) and the desired gap dimension S, as well as the length L5 of the center section 5 a and the length L6 of both rolling bearings 6, the roll grinder 1 is subsequently assembled from the above components. In this process, a rolling bearing 6, a spacer 4 and a roller 2 are fitted onto each bearing section 5 b of the axle 5 extending through the central bore 3 c of the handle body 3, so that the inner ring of the rolling bearing 6 is supported on the central section 5 a of the axle 5 and the spacer 4 is fixed between the inner ring of the rolling bearing 6 and the inside of the roller 2. Then, the roller 2 is firmly and non-detachably connected to the axle 5 by press-fitting so that an interference fit is obtained at the connection points. The outer ring of the rolling bearing 6 is fixed to the handle body 3 by force-fitting and, if necessary, by positive fitting.

Second Embodiment (FIGS. 2 and 4)

In the second embodiment, described below with reference to FIGS. 2 and 4 , the roll grinder 1 includes substantially the same components and features as the roll grinder 1 of the first embodiment, except for the following differences:

Whereas in the first embodiment the grinding and polishing surfaces 1 a, 1 b are integrally formed on the end faces with the rollers 2 at the end faces thereof and are thus an integral part of the roll grinder 1, the roll grinder 1 according to the second embodiment includes separate grinding/sharpening and polishing discs 7 on the end faces, of which the grinding and polishing surfaces 1 a, 1 b are formed. The grinding and polishing disks 7 may be detachably connected to the roller 2 or to the axle 5 by screwing formed threaded studs 7 b into corresponding mating threads. In deviation from the first embodiment, the rollers 2 are not chamfered or rounded on the outward-facing end face, so that the lateral areas 7 a of the grinding and polishing discs 7 merge in a flush manner with the lateral area 2 a of the respective adjacent roller 2. Instead, the grinding and polishing discs 7 are each chamfered or rounded at the transition between the lateral surface 7 a and the respective grinding or polishing surface 1 a, 1 b. The radius of curvature at the end face of the grinding or polishing disc 7 is, for example, in the range from 0.5 mm to 2 mm and is preferably about 1 mm.

LIST OF REFERENCE SIGNS

-   -   1 roll grinder/rolling sharpener     -   1 a grinding/sharpening surface     -   1 b polishing surface     -   2 roller/running roller     -   2 a lateral area/shell or circumferential side     -   2 b opening     -   3 handle body     -   3 a lateral area/shell     -   3 b end face     -   3 c boring     -   3 d bearing support section     -   4 spacer     -   5 axle     -   5 a center section     -   5 b bearing section     -   6 bearing     -   7 grinding/polishing disc     -   7 a lateral area/shell     -   7 b threaded stud     -   8 rubber ring     -   A distance between rollers     -   L length of handle body     -   L1 distance of bearing support sections     -   L2 distance from bearing support section to end face     -   L4 length of spacer     -   L5 length center section of axle     -   L6 length of rolling bearing     -   S gap between end face of handle body and roller     -   U base     -   X1 rotational/center axis of roll grinder     -   X3 rotational/center axis of handle body     -   X5 rotational/center axis of axis, bearing, if necessary         grinding/polishing disc 

1-15. (canceled)
 16. A method for producing a roll grinder with two rollers, a handle body arranged between the rollers and rotatable relative thereto, and with at least one grinding or polishing surface, the method comprising: producing the handle body; measuring the handle body so as to determine a dimension of the handle body; providing at least two differently dimensioned types of spacer elements, each of which enables determination of a different distance between one of the rollers and the handle body in the assembled state of the roll grinder; selecting one of the types of spacer elements depending on the measured dimension of the handle body; and connecting the handle body to the rollers to form the roll grinder using at least one spacer element of the selected type.
 17. The method according to claim 16, wherein the handle body is made of plastic, metal, or wood.
 18. The method according to claim 16, wherein the handle body is made of plastic, metal, or wood in once piece.
 19. The method according to claim 16, wherein the handle body is made of wood, and a moisture content of the wood is at most 15%.
 20. The method according to claim 16, wherein the handle body is manufactured as a cylinder.
 21. The method according to claim 16, wherein the measured dimension is a distance between two parallel sides of the handle body.
 22. The method according to claim 16, wherein the rollers are made of plastic or metal.
 23. The method according to claim 16, wherein each of the rollers is connected, with the interposition of a spacer element of the selected type, to an axle so as to be rotatably mounted on or in the handle body.
 24. The method according to claim 23, wherein each of the rollers is non-rotatably connected to the axle.
 25. The method according to claim 23, wherein the axle is a stepped axle with a central section and two bearing sections stepped at the ends, and wherein a rolling bearing, one of the spacer elements, and one of the rollers are arranged on each bearing section.
 26. The method according to claim 25, wherein, for each rolling bearing the rolling bearing is axially supported on the central section or the spacer element is axially fixed between the rolling bearing and the roller.
 27. The method according to claim 25, wherein each rolling bearing is mounted on the handle body so as to be supported by an outer ring on the handle body or by a bearing sleeve arranged thereon.
 28. The method according to claim 16, wherein at least one of the rollers has an end face-side grinding or polishing surface.
 29. The method according to claim 16, wherein at least one grinding or polishing disc is attached to the roll grinder, the grinding or polishing disc having a grinding or polishing surface.
 30. The method according to claim 29, wherein the grinding or polishing disc is detachably mounted on the roller or an axle that the roller is connected to.
 31. The method according to claim 16, wherein each of the rollers has a rubber ring running circumferentially at an edge of the roller, which forms a running surface of the roller.
 32. The method according to claim 16, wherein the roll grinder is manufactured from a maximum of 14 components, the components comprising: the two rollers, the handle body, two spacer elements, an axle, two rolling bearings, two rubber rings, and at least one grinding or polishing disc.
 33. A method for producing a plurality of roll grinders by performing several times the method according to claim 16, wherein at least two handle bodies are produced, wherein each handle body is connected to two rollers to form a roll grinder, using at least one spacer element of the type selected on the basis of the measured dimension of the handle body, thereby maintaining the distance between each of the rollers and the handle body within identical tolerance ranges in all the roll grinders.
 34. The method of claim 33, wherein the distance between the handle body and each of the rollers is smaller than 0.5 mm. 